62-66Thermal bonded
polyester staple fibre nonwoven fabrics have been produced, considering
different proportions of binder fibres, directions of web laid as variables,
and bonding time and bonding temperature as constant. The influence of process
variables on fabric properties, such as bursting strength, air permeability,
bubble point diameter, mean flow pore diameter and filtration efficiency with
three different particle (1, 0.5, and 0.3µ) along with the overall filtration
efficiency have been tested and the results are compared with spun laced
nonwoven fabrics. The fibres are oriented in cross and
parallel directions, this arrangement of fibres leads to increase in bursting
strength. The trend in air permeability of cross-laid web fabrics is found
similar to spunlaced fabrics. The pore sizes of the thermal bonded fabrics have
been minimized by laying the web in cross direction and increasing the binder
fibre proportion; it has minimum variation with spunlaced fabrics. Aerosols of
different particles are fed to the upstream of the filters with the face
velocity of 16.6 cm/s which is then maintained as constant. The maximum
filtration efficiency achieved is found to be 93.13% which is around 13% higher
than that of the spunlaced fabric. For 80g/m2 fabrics with 0.3µ
particles, the filtration efficiency of spun laced fabric is only 38% which is
around one and a half time lesser than 80 g/m2 of thermal bonded
fabric; 90g/m2 fabrics show equal and better properties than 100g/m2
fabrics